We define men and women not simply as biologically different, but as ‘opposite’ sexes; we even refer on occasion to ‘the battle of the sexes’. Men and women are polarized in our culture, as opposite, unequal, and at war in a classic example of dual symbolic classification. This is an old theory, rooted in Graeco-Roman and Judaeo-Christian culture, and was clearly formulated by Aristotle and re-formulated by Aquinas. Plato, however, argued that the sexes are different, but complementary, and (relatively) equal, and framed an egalitarian tradition which has persisted, and connects with, the egalitarian tradition in Christianity.